Season tuna with salt and a bit of grape seed oil. Roll in sesame seed and pepper mixture. Put grape seed oil in cast iron pan and heat to a high temp, add tuna, cook for 2 minutes on each side. Turn off heat and let tuna sit in pan on uncooked sides for 2 minutes.
Serve with wasabi sauce. Mix Cream or mayo with wasabi add fish sauce, maple syrup, sambal and soy sauce.